Mounting FUSE filesystems as unprivileged user
The short answer is that this is possible but depends on the
setuid fusermount
binary, which is called by the user
as a sub-process:
$ ls -l /usr/bin/fusermount3
-rwsr-xr-x 1 root root 35200 Mar 23 2022 /usr/bin/fusermount3
For example when using the
mountpoint-s3 utility,
the call is in
https://github.com/awslabs/mountpoint-s3/blob/main/vendor/fuser/src/mnt/fuse_pure.rs
which can be in action by strace
-ing the mount call:
10558 execve("/usr/bin/fusermount3", ["fusermount3", "-o", "rw,nosuid,nodev,noatime,default_"..., "--", "/home/bnikolic/s3work"], 0x557d5b9173d0 /* 34 vars */) = 0